I only skimmed through this thread, but I'd have to say I side with Adorama on this one. Actually, I think Amazon should take some blame for this, though I'm not sure what the "right" solution is.
The consumers: There's no real way to determine who is a good faith buyer versus someone who saw an opportunity and took advantage of it. There's a case to be made where someone bought only one or two batteries for himself versus a person who purchased 25. However, that's not completely sound and is not proof positive.
Adorama: Adorama seemingly was not at fault for this mistake, yet is bearing the cost of refunding shipment return labels. That's above and beyond customer service, in my book.
Amazon: Seemingly the true culprit. If anything, Amazon should bear the cost of making Adorama whole by paying for the additional incurred costs that Adorama is paying. As for making consumers whole, I don't know what Amazon can do to be fair.
Amazon could fill the orders themselves from their own warehouses/stock and take the hit of any losses due to their mistake. But then, the consumers who took advantage of the system receive a windfall that doesn't settle well with me. To me, it's almost like receiving stolen goods. If the price is too good to be true, then something must be up. Take advantage of the system and you've committed some wrong yourself.